Load bearing device including overload indicator

ABSTRACT

Load-bearing devices, each including an overload indicator of the present invention interconnecting load bearing connectors, preferably elongated load bearing connectors are provided. In preferred embodiments, the load bearing connectors are chains, ropes, wire ropes, cables, straps and the like, preferably chain. The wire form overload indicator preferably includes a modified wire form link, preferably either a modified welded link or a modified quick link, generally having a first thickness and first and second elongated sides. The modified link preferably includes two elongated sides, one of which preferably has a portion having a diminished thickness narrower than the first thickness. The diminished thickness preferably has a generally predetermined load bearing capacity or capability and is calibrated to reduce the load bearing capacity or capability of the overload indicator. Methods of making an overload indicator and a load bearing device including an overload indicators of the present invention are also disclosed.

RELATED APPLICATIONS

The present application is a continuation-in-part application of U.S.patent application Ser. No. 10/460,903, filed Jun. 13, 2003 and entitledLoad Bearing Device Including Overload Indicator, which claims thebenefit of U.S. Provisional Application No. 60/388,881, filed Jun. 14,2002, both of which are hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION

Chain and other elongated lifting and load-bearing devices such as rope,wire rope, cables, straps and the like are often used eitherintentionally or unintentionally up to and beyond their ratedload-bearing capacity or working capacity. When chain and the like areused in this way, and the rated capacity is exceeded, the chain or otherlifting or load-bearing elongated devices may fail. When the failureoccurs, other damage may be associated with the event and, in certaincircumstances, there are attempts to recover damages based uponliability associated with failure of the chain or other load bearingdevices. In these circumstances, it would be helpful to determinewhether the rated load bearing capacity for the chain or other elongatedlifting or load bearing device has been exceeded; if so, it is believedthat the failure to stay within the rated load bearing capacity willprovide important exculpatory evidence for use in defending claims ofliability against manufacturers of the chain or other load bearingdevices.

For that reason, it is believed that a device for incorporation into, orfor use in association with, a chain or other elongated load bearingdevice would have value in the industry if it was capable of indicatingwhen the rated load bearing capacity or working capacity of the chain orother elongated load bearing device is exceeded. While devices thatindicate load exist, these devices are relatively cumbersome and eitherawkward to use or so expensive as to make use as an indicator ofexceeded load bearing capacity impractical for commercial uses.

While load cells are a possibility, they are relatively expensive andthey also generally require a source of electricity. Incorporation ofsuch an indication device into an elongated load-bearing device such asa rope, chain or other simple load bearing device is believed to beimpractical unless the cost of such devices can be significantly reducedand the challenge of providing electricity to the device is resolvedsimply and effectively.

The present invention provides simple and reliable solutions to theseand other problems.

SUMMARY OF THE INVENTION

The present invention provides a load bearing device calibrated toprovide an indication of a load borne by a load bearing device thatexceeds a load bearing capacity or rating established for the loadbearing device. The load bearing device includes first and second loadbearing connectors interconnected by an overload indicator. The overloadindicator is calibrated to provide an indication of a load borne by theload bearing device that exceeds a load bearing capacity established forthe load bearing device. The overload indicator is preferably a modifiedquick link. The modified quick link preferably includes a strand of wireform material having first and second ends, the first and second endsdefining a gap between the respective first and second ends. Thepreferred modified quick link will further include a disconnectableconnector connecting the first and second ends of the strand of wireform material to form a continuous loop, when the connector is connectedto each of the respective first and second ends. The strand of wire formmaterial includes a first portion having a first thickness containing afirst amount of wire form material in a perpendicular cross-sectionpassing through a length of the strand; the first portion being adjacentto a second portion including a diminished segment having a secondamount of wire form material in a perpendicular cross-section passingthrough a length of the strand which is less than the first amount ofwire form material; wherein the diminished segment of the second amountof wire form material is calibrated in such a manner as to establish aprojected load, which, when borne by the overload indicator, will createa sufficient force to break the overload indicator proximate thediminished segment.

In preferred embodiments, a load bearing device of the present inventionincludes a safety loop interconnecting the first and second load bearingconnectors, so that a secondary load bearing alternative is provided ifthe overload indicator, which bears the load borne by the respectiveload bearing connectors, breaks. The safety loop will then bear theload, unless the load exceeds the load which can be borne by the safetyloop. In other embodiments, the overload indicator is marked with aserial number to identify it. In preferred embodiments, a load bearingconnector may also be marked with a serial number so that the overloadindicator attached to the particular load bearing device made by themanufacturer can be correlated to help manufacturers determine whetherthe load bearing device has been manipulated by the consumer in any wayto hide evidence of an excessive load exceeding the rated capacity ofthe load bearing device or the overload indicator.

A wire form load indicator is provided for interconnection of loadbearing connectors, preferably elongated load bearing connectors, havingconnection loops for bearing a load. In preferred embodiments, the loadbearing connectors are chains, ropes, wire ropes, wires, cables and thelike, preferably chain. The wire form overload indicator preferablyincludes a wire form chain-link having a first thickness, first andsecond elongated sides and rounded ends. The first elongated sidepreferably includes an interconnectable gap through which connectionloops of the load bearing connectors can pass when the interconnectablegap is unconnected. The interconnectable gap preferably includes aconnection end and a connectable end, the connecting end having aturnable connector capable of connecting the connecting end to theconnectable end to close the gap. In preferred embodiments, theconnectable end is threaded and the connector has reciprocating threadscapable of receiving the threaded connectable end in order tointerconnect the respective ends by “screwing” the turnable connector onto the threaded connectable end, close the gap and complete the loop inthe chain-link. The second elongated side preferably has a portionhaving a diminished thickness as compared to the first thickness. Thediminished thickness preferably has a predetermined load bearingcapability and is calibrated to reduce the load bearing capability ofthe overload indicator, as compared to the load bearing capability of achain length and each chain-link in the chain length having a generallyconsistent thickness equivalent to the first thickness, wherein thepredetermined load bearing capability of the diminished thickness iscalibrated so that if the overload indicator breaks apart proximate thediminished thickness, such breakage will indicate that the load borne bythe overload indicator exceeds the predetermined load bearing capacityof the diminished thickness.

The present overload indicator has been designed with the objective ofproviding manufacturers with an indicator capable of providing warningto the user of a load bearing device regarding the rated capacity of theload bearing device and post-failure evidence of a load exceeding therated load bearing capacity of a chain or other elongated load bearingdevices. The present overload indicator can have a diminished thicknesswhich is calibrated to provide for predetermined breakage when bearing aload in excess of any of a number of rated load bearing capacities forany number of different chains or elongated load bearing devices.

In an alternative embodiment, the overload indicator is preferably amodified welded link. In preferred alternative embodiments, the loadbearing device of the present invention includes a safety loopinterconnecting first and second load bearing connectors so that asecondary load bearing alternative is provided if the overloadindicator, which bears the load borne by the respective load bearingconnectors, breaks. As discussed above, the safety loop will bear theload unless the load exceeds the load which can be borne by the safetyloop. In these alternative embodiments, the overload indicator ispreferably marked with a serial number to identify it. In preferredembodiments, one or two of the load bearing connectors are also markedwith a serial number so that the overload indicator attached to theparticular load bearing device made by the manufacturer can becorrelated with the respective connectors to help manufacturersdetermine whether the load bearing device has been manipulated by theconsumer in any way to hide evidence of an excessive load exceeding therated capacity of the load bearing device or the overload indicator.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, in which like reference numerals and letters indicatecorresponding parts throughout the several views,

FIG. 1 shows an alternate load bearing device 2 including an overloadindicator 8 of the present invention having a diminished thickness atnotch 30 on a first elongated side 12;

FIG. 2 shows a further alternate overload indicator 8 a, similar to thatshown in FIG. 1, but having a diminished thickness B (See FIG. 3) atnotch 30 a that is less diminished as compared to the uniform thicknessA of the strand 10, than the diminished thickness at notch 30 shown inFIG. 1;

FIG. 3 is an enlarged view of a portion of the overload indicator 8 ashown in FIG. 2, showing a diminished thickness B of the strand 10 ofwire form material in the area of notch 30 a;

FIGS. 4, 5 and 6 show a series of strands 10 of alternate overloadindicators of the type shown in FIG. 2, except that the thickness of therespective strands 10 at the respective notches 30 b, 30 c, 30 d variesas does the amount of wire form material remaining in the respectivestrands 10 in a perpendicular cross-section passing through a length ofthe respective strands 10 at the narrowest point created by therespective notches 30 b, 30 c, 30 d;

FIGS. 7, 8, 9, 10, 11 and 12 show additional strands 10 of wire formmaterial of overload indicators of the type shown in FIG. 2, except thatthe amount of wire form material through a perpendicular cross-sectionpassing through a length of the respective strands are diminished byremoving wire form material from the respective strand by drilling avariable hole 36 a, 36 b, 36 c, 36 d, 36 e, 36 f through the respectivestrands so that the load bearing capacity of each respective overloadindicator will also vary according to the amount of wire form materialremaining in a perpendicular cross-section passing through a length ofthe respective strand 10 at the center of the respective hole;

FIG. 13 shows a portion of a strand 10 of an alternate overloadindicator having an alternate notch 30″ consisting of a v-cut;

FIG. 14 shows a portion of a strand 10 of an alternate overloadindicator having an alternate notch 30′″ consisting of a saw-cut;

FIGS. 15A and 15B show a prior art quick link 9 shown in a connectedconfiguration in FIG. 15A and an unconnected configuration in FIG. 15B;

FIGS. 16 A, B, C and D show graphical representations of data reportedin Tables 1, 2, 3 and 4, respectively, and FIG. 16E provides a furthergraphical representation of data reported in Table 3;

FIG. 17 shows an alternate load bearing device 102 including analternate overload indicator 108 of the present invention;

FIG. 18 shows a further alternate overload indicator 108 a, similar tothat shown in FIG. 16, but having a diminished thickness D (See FIG. 19)at notch 130 a that is less diminished as compared to the uniformthickness C of the strand 110, than the diminished thickness at notch130 shown in FIG. 17;

FIG. 19 is an enlarged view of a portion of the alternate overloadindicator 108 a shown in FIG. 18, showing a diminished thickness D ofthe strand 110 of wire form material in the area of the notch 130 a;

FIGS. 20, 21 and 22 show a series of strands 110 of alternate overloadindicators of the type shown in FIG. 18, except that the thickness ofthe respective strands 110 at the respective notches 130 b, 130 c, 130 dvaries as does the amount of wire form material remaining in therespective strands 110 in a perpendicular cross-section passing througha length of the respective strands 110 at the narrowest point created bythe respective notches 130 b, 130 c, 130 d;

FIGS. 23, 24, 25, 26, 27 and 28 show additional strands 110 of wire formmaterial of alternate overload indicators of the type shown in FIG. 18,except that the amount of wire form material through a perpendicularcross-section passing through a length of the respective strands arediminished by removing wire form material from the respective strand bydrilling a variable hole 136 a, 136 b, 136 c, 136 d, 136 e, 136 fthrough each of the respective strands so that the load bearing capacityof each respective alternate overload indicator 108 will also varyaccording to the amount of wire form material remaining in aperpendicular cross-section passing through a length of the respectivestrand 110 at the center of the respective hole;

FIG. 29 shows a portion of a strand 110 of an alternate overloadindicator having an alternate notch 130″ consisting of a v-cut;

FIG. 30 shows a portion of a strand 110 of an alternate overloadindicator having an alternate notch 130′″ consisting of a saw-cut; and

FIGS. 31A and B show graphical representation of data reported in Tables5 and 6, respectively.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIG. 1, a load bearing device 2 of the presentinvention having first and second load bearing connectors 4, 6interconnected by an overload indicator 8 to create a three-link safetyloop 11 is shown. The preferred embodiment shown in FIG. 1 is a chain 2including a modified quick link 9. Referring now also to FIG. 2, theoverload indicator 8 of the present invention is preferably made from amodified quick link 9 in which an amount of wire form material in asegment or a portion of a strand 10 of wire form material of the quicklink 9 is diminished in one of a number of ways that result in a strandof wire form material that has a segment where the strand is weaker thanin other segments of the strand and is therefore projected to break inthis segment containing the diminished amount of material. The strand 10of wire form material, including first and second elongated sides 12,14, and a connector 16 that is secured to a connectable end 24 of thestrand of wire form material. It will be appreciated that the overloadindicator 8 can be effectively interconnected to any two chain links ina chain that are not otherwise interconnected by a single chain link,thereby creating a safety loop of at least two links, preferably threeand any greater number than three except as may be limited by cost andother practical concerns.

Referring now also to FIGS. 3-6, it will be appreciated that one of theways a segment of the strand 10 of wire form material can be diminishedto form a modified quick link 9 is to machine one of the elongated sides12 to form a rounded notch 30 a, 30 b, 30 c, 30 d, as shown. The strand10 has a generally uniform thickness A, which is measurable through across-section of the strand 10 generally perpendicular to the length ofthe elongated side 12. The thickness B of the strand 10 at the notch 30a can also be measured in a similar manner and it will be less than thethickness A of the other segments of the strand 10. In preferredembodiments, the thickness of the notch 30 will be less than about 70%of the thickness of the other segments of the strand 10.

Referring now also to FIGS. 7-12, such an elongated side 12 may also bedrilled out, preferably in the center of the wire form material to formopenings or holes 36 a, 36 b, 36 c, 36 d, 36 e, 36 f. The thickness A′of the strand 10 is generally measured across a cross-section of thestrand 10 perpendicular to the length of the elongated side 12 of thestrand 10. The thickness of the remaining material on either side of thehole or opening 136 is determined by measuring the inside diameter B′ ofthe respective hole and subtracting that from the thickness A′ of thestrand 10 to determine the thickness of the remaining material.

In yet further embodiments, further notches in the elongated sides 12will also diminish the amount of wire form material in the diminishedsegment of the strand 10. Referring now also to FIGS. 13 and 14, aV-shaped notch 30″ made by a machining tool such as a mini-broach or thelike may also be provided (see e.g. in FIG. 13), as can a saw-cut notch30′″ made by a saw blade (see e.g. in FIG. 14). The thickness B″, B′″ ofthe respective notches 30″, 30′″ and the thickness A″, A′″ of the strand10′ in each case are measured in the same manner as discussed above inrelation to the overload indicators 8 a-8 d discussed in relation toFIGS. 2-6. It will be appreciated that other ways of reducing thematerial present in the strand 10 of wire form material may be employedso long as the amount of wire form material is reduced as compared to anadjacent segment of the strand 10. While machining and cutting may beused, it will also be appreciated that the strand of wire form materialcould be formed to have a diminished amount of wire form material in onesegment as compared with the other segments that had a greater amount ofmaterial. In this way, a diminished segment could be created withoutmachining or cutting the strand in any way.

Depending on the amount of material present, the thickness of theremaining material, or any other measure of diminished material presencethat correlates with break strength, it is believed that the modifiedquick links 9 or overload indicators 8 can be calibrated based on ameasure of this diminished material to provide an indication of a loadborne by the load bearing device 2 that exceeds a load bearing capacityor noting established for the load bearing device 2.

Referring now also to FIGS. 15A and 15B, the overload indicator 8 of thepresent invention is preferably made from a quick link 9 of the typeshown in FIGS. 15A and 15B. Quick links of this type are commerciallyavailable from Mizumoto Machine Manufacturing Co., Ltd., Himeji-City,Japan and elsewhere. Although quick links of various kinds are availablein the market place, the strands of wire form material in such productsare generally made from SAE 1008 steel containing 0.08% carbon content.The quick link 9 has a strand 10 of wire form material, including firstand second elongated sides 12, 14, and a connector 16 that is secured toa connecting end 22 of the strand of wire form material. At the otherend of the strand 10 of the quick link 9 is a connectable end 24,including a threaded exterior surface 25. The connecting end 22 and theconnectable end 24 define a gap in the strand 10 which is bridged whenthe connector 16 is secured to the connectable end 24 by securingreciprocating threads 26 of the connector 16 to the threaded exteriorsurface 15 of the connectable end 24. Quick links of this kind are wellknown in the art. It will be appreciated that the connector 16 issecured to the connectable end 24 by rotating the connector 16 so thatthe threaded exterior surface 25 of the connectable end 24 becomesengaged with the reciprocating threads 26 of the connector 16.

Referring now also to FIGS. 2-6, an alternate load bearing device of thepresent invention may include any one of a series of overload indicators8 a, 8 b, 8 c, 8 d in which the strand 10 of the quick link 9 isdiminished by creating a notch 30 a, 30 b, 30 c, 30 d in the strand 10to diminish the thickness of the strand and diminish the amount of wireform material in a perpendicular cross-section passing through a lengthof the strand through the narrowest portion of the strand 10 at therespective notch 30 a, 30 b, 30 c, 30 d. This narrowing of the thicknessof the strand, or, in an alternate embodiment discussed below, thereduction in the amount of wire form material in the strand 10, isbelieved to reduce the strength of the strand 10 at the point of thisnarrowing or reduction of material so as to create a weakness in thestrand 10 where the strand 10 will break in a predictable manner, whenexposed to loads which exceed the load bearing capacity of the strand10. This load bearing capacity can be calibrated as discussed below inorder to provide an overload indicator 8 which will indicate that anestablished load bearing capacity for a particular load bearing device 2including an overload indicator 8 has been exceeded when such a loadbearing device 2 is exposed to an excessive load.

Although the load bearing device shown in FIG. 1 is essentially a chainhaving a series of chain links and an overload indicator 8 of thepresent invention, it will be appreciated that the load bearingconnectors 4, 6 may also be made of other load bearing connectors suchas cables, straps, ropes, wire ropes and the like that areinterconnected with the overload indicator of the present invention.Although not required, the safety loop 11 shown in FIG. 1 is preferred.Any number of equivalent safety loops may be used in association withalternate load bearing devices including safety loops made from ropes,wire ropes, cables, straps and the like that are secured to therespective load bearing connectors to secure them if the overloadindicator is exposed to an excessive load and subsequently breaksfollowing such exposure.

Referring now also to FIGS. 13 and 14, the notch 30 of the presentinvention may be a narrowing in the strand 10 of a quick link created bya grinding device of one type or another or by any other type of devicethat will remove material to either create a narrowing in the strand orsimply reduce the amount of wire form material in a certain thickness ofthe strand 10 of a quick link. In FIGS. 13 and 14, two somewhatdifferent notches, 30″ and 30′″, are shown. These notches are a v-cutnotch 30″ and a saw-cut notch 30′″. In each case, the amount of materialat the narrowest point of the respective notch is reduced, therebyreducing the breaking force required to break the strand at therespective notch. In the present application, the term “notch” means anarrowing in a strand of wire form material. The narrowing may becreated either by cutting away existing material in a pre-formed strandof wire form material, or, alternately, by creating a strand of wireform material having a narrowing.

Referring now also to FIGS. 7-12, the overload indicator 8 of thepresent invention may also include a segment of a strand 10 of wire formmaterial in which the amount of wire form material in a horizontal planepassing through the strand 10 of wire form material is reduced bydrilling a hole 36 or otherwise creating an opening 36 in the strand 10of wire form material. In this way, the amount of wire form material inthis particular strand of wire form material is reduced so as to reducethe breaking force required to break the strand at this particularsegment. It will be appreciated that a series of openings or holes,having a variety of shapes, may be created in a strand of wire formmaterial to reduce the amount of material in the strand, therebyreducing the breaking force required to break the strand. In each case,it is believed that the amount of force required to break the strand 10at the point at which the amount of wire form material in the strand isreduced can be calibrated so as to create a predictable breaking forcethat will break the strand when such a force is borne by the strand. Inthis way, a series of overload indicators 8 may be created, calibratedand used to provide an indication of the exposure of a load bearingdevice to a load which exceeds an established load bearing capacity forthe particular load bearing device 2. It will be appreciated, that loadbearing devices of the present invention, each of which include anoverload indicator of the present invention, will provide an indicationto manufacturers when their load bearing devices have been misused bypurchasers. In particular, if a load bearing device having a specificload bearing rating is used and exposed to a load greater than theestablished load bearing capacity for which the load bearing device israted, the overload indicator will break, providing clear evidence ofits exposure to a load exceeding the established load bearing capacity.

Furthermore, as noted in FIGS. 1 and 2, in preferred embodiments, theoverload indicator will also include a serial number 40 which is etched,stamped or otherwise imprinted on the load bearing device. The sameserial number will also be secured to the respective load bearingconnectors 4, 6, so that upon failure of the overload indicator, effortsto replace the overload indicator with a different overload indicatorcan be monitored and detected.

As indicated above, the overload indicator 8 will have a serial number40 to identify the particular overload indicator 8. In preferredembodiments, the load bearing connector may also have a serial number 40so that the load bearing device may be identified and correlated withthe particular overload indicator 8 interconnecting the respective loadbearing connectors of the load bearing device with the overloadindicator actually incorporated in the device by the manufacturer. Itwill be appreciated that utilizing these serial numbers will providemanufacturers with information to help control tampering by usersfollowing exposure of a load bearing device 2 or overload indicator 8 toa load which exceeds the working capacity or rated capacity set for theparticular indicator 8 or device 2.

In preferred embodiments, the strand 10 of wire form material used tomake the quick link 9 for modification to be an overload indicator 8,will be made of steel containing at least about 0.12% carbon, preferablyat least about 0.16% carbon, most preferably about 0.22% carbon andsufficiently heat treated to raise the tensile strength of the overloadindicator 8 to that sufficient to meet tensile strength requirements forinclusion in an overhead chain load bearing device in the United Statesof America. It will be appreciated that heat treating is an art that iswell known and that those of skill in the art can achieve the goal theywish to achieve when they are asked to heat treat a higher carbon steelof the type discussed. Heat treating generally involves heating thesteel to a temperature of at least about 1600 degrees F. or until thesteel is “red hot”. The heat is then quickly dissipated, by placing thesteel in a cooler liquid to “quench” the heat. The steel is thentempered by heating the steel again. Each type of steel is treatedsomewhat differently, however. Many approaches may be taken, most ofwhich are well know in the art.

The present overload indicator 8 preferably includes first and secondelongated sides 12, 14 and a connector 16, interconnected with aconnecting end 22 of the overload indicator, preferably for threadableconnection to a connectable end 24 of the overload indicator to close agap (not shown), which exists between the connecting end 22 and theconnectable end 24 of the overload indicator 8. In preferredembodiments, the overload indicator will have a notch 30 in the secondelongated side that creates a narrowing in the wire formed materialwhich reduces the strength of the material and the load bearing capacityof the material at that point. The amount of material that is removed increating the notch may be varied and the amount of material whichremains will correlate with the amount of the load bearing capacity ofthe preferred overload indicator.

In alternate embodiments of the present invention shown in FIGS. 17-28,the overload indicator 108 may be an ordinary welded chain link, asopposed to a quick link, diminished in the respective manners discussedherein. The step of diminishing the amount of material in a portion ofthe strand of wire form material may occur either before or after thechain link is welded our otherwise secured within the load bearingdevice 102 (See discussion below).

EXAMPLE 1

Quarter-inch commercially available quick links made from low carbonsteel (SAE 1008 STEEL or the equivalent) were machined to create notchesof various depths generally in the center of the side of the quick linkopposite the connector to form overload indicators of the presentinvention. These modified quick link samples were incorporated into loadbearing devices by connecting them to a 7MM grade 70 chain having arated load bearing capacity of 3,150 pounds. The overload indicatorswere connected to the chain to become a load bearing component betweentwo connecting links of separate load bearing connectors separated bythree links of the chain that no longer bore the load and became thesafety loop connected to the two connecting links of the load bearingconnectors. The thickness of the remaining wire form material at thenarrowest point at the bottom of the notch was measured using an opticalcomparator. The load bearing devices made with each of the respectiveoverload indicator samples was tested to determine its peak load byplacing a continuously increasing load upon each load bearing sampleusing a Satec Tensile Strength Tester. The data for breaking strengthwas plotted against remaining material thickness at the notch togenerate a best fit line showing the relationship between break strengthand remaining material thickness at the notch. The correlationcoefficient for the line relative to the data was determined to be0.9947 which was believed to be acceptable. The data is reported inTable 1 and a plot of the data reported in Table 1 is shown in FIG. 16A.TABLE 1 Material Material Thickness Break Thickness at as a percent (%)Strength Test Notch of Original Diameter (breaking No. (inches) (dia.)force) (LBS) Break Type 1 0.179 76% 6004 End Shear 2 0.150 64% 4877Notch Shear 3 0.088 37% 3180 Notch Shear 4 0.078 33% 2885 Notch Shear

EXAMPLE 2

Quarter-inch commercially available quick links made from SAE 1008 steelwere cut with a saw blade to create notches of various depths and todiminish the wire form material generally in the center of the side ofthe quick link opposite the connector to form overload indicators of thepresent invention. These modified quick link samples were incorporatedinto load bearing devices by connecting them to a 7MM grade 70 chainhaving a rated load bearing capacity of 3,150 pounds. The overloadindicators were connected to the chain to become a load bearingcomponent between two connecting links of separate load bearingconnectors separated by three links of the chain that no longer bore theload and became the safety loop connected to the two connecting links ofthe load bearing connectors. The thickness of the remaining wire formmaterial at the narrowest point at the bottom of the notch was measuredusing an optical comparator. The load bearing devices made with each ofthe respective overload indicator samples was tested to determine itspeak load by placing a continuously increasing load upon each loadbearing sample using a Satec Tensile Strength Tester. The data forbreaking strength was plotted against remaining material thickness atthe notch to generate a best fit line showing the relationship betweenbreak strength and remaining material thickness at the notch. Thecorrelation coefficient for the line relative to the data was determinedto be 0.9963 which was believed to be acceptable. The data is reportedin Table 2 and a plot of the data reported in Table 2 is shown in FIG.16 B. It is believed that correlation coefficient will begin to fall offwhen sample overload indicators have notches where less than about 25%of the original material thickness is diminished. TABLE 2 ¼″ QUICK LINKTESTING MATERIAL % OF ORIGINAL NOTCH NOTCH NOTCH ORIGINAL THICKNESSBREAKING MATERIAL n WIDTH DEPTH RADIUS WIRE DIA. AT NOTCH FORCETHICKNESS 1 0.1589 0.1058 0.0324 0.2402 0.1344 5,009 56% 2 0.1591 0.10260.0318 0.2402 0.1376 5,061 57% 3 0.1623 0.1048 0.0319 0.2401 0.13534,866 56% 4 0.2147 0.1527 0.0318 0.2405 0.0878 2,962 37% 5 0.2156 0.14940.0304 0.2404 0.0910 2,847 38% 6 0.2169 0.1552 0.0285 0.2408 0.08562,883 36% 7 0.2737 0.2013 0.0391 0.2401 0.0388 672 16% 8 0.2725 0.19870.0353 0.2400 0.0413 700 17% 9 0.2739 0.1980 0.0351 0.2401 0.0421 60918%

EXAMPLE 3

Commercially available quarter-inch quick links made from SAE 1008 steelwere drilled generally through the center of the wire opposite theconnector on the quick link with a series of drill bits of various sizesto determine a predicted hole size (diameter) that would result in abreak at a project load of 3,150 lbs. The actual hole or opening sizeand the amount of remaining wire form material remaining on each side ofthe hole or opening were measured using an optical comparator. The peakload for each drilled quick link was measured by placing a continuouslyincreasing load upon each drilled link sample using a Satec TensileStrength Tester. The data for breaking strength was plotted against holesize to generate a best fit line showing the relationship between breakstrength and hole size. The correlation coefficient for the linerelative to the data was determined to be 0.9470 which was believed tobe acceptable. The equation for the line was y (breakstrength)=25,077×(hole diameter)+5889.6. This equation was used todetermine a hole size projected to achieve a 3,150 lbs. peak load. Thedata is reported in Table 3 and a plot of the data reported in Table 3is shown in FIG. 16 C. The projected hole size for a 3,150 lbs. loadbearing capacity was a hole or opening having a 0.1092 inch diameter. Itis generally believed that a 7/64ths inch drill bit will generallygenerate a hole having a diameter of 0.1094 inch. In order to confirmthis result, six quarter-inch quick links made from SAE 1008 steel weredrilled generally through the center of the wire opposite the connectoron the quick link with a 7/64ths inch drill bit. The peak load for eachof these samples was measured by placing a continuously increasing loadupon each drilled link sample using a Satec Tensile Strength Tester asreported above. The data from these measurements is reported in Table 4below and presented graphically in the bar graph shown in FIG. 16 D. Theaverage of the six peak load measurements is within 2.016% of the targetpeak load. Peak load is also plotted against remaining materialthickness, each reported in Table 3, in the graph shown in FIG. 16 E.TABLE 3 Size of Actual Hole Remaining Material Peak Drill Bit I.D. 2sides Load 100 DIA 0.094 0.122 3323 120 DIA 0.118 0.113 2973 140 DIA0.141 0.105 2425 160 DIA 0.159 0.086 2237 180 DIA 0.181 0.072 1425 200DIA 0.198 0.043 611

TABLE 4 Specimen Peak Target Working Maximum Specimen Size of SampleGage Length Load Load Limit (WLL) Elongation Identification Wire NO 11.83 3,337 3,150 36.27 HOLE BREAK ¼″ NO 1 1.83 3,542 3,150 38.04 HOLEBREAK ¼″ NO 3 1.83 3,093 3,150 37.22 HOLE BREAK ¼″ NO 4 1.83 3,134 3,15037.64 HOLE BREAK ¼″ NO 5 1.83 3,149 3,150 35.22 HOLE BREAK ¼″ NO 6 1.833,026 3,150 49.22 HOLE BREAK ¼″AVERAGE: 3,214ST DEV: 191.5

A broken load measuring device (not shown) connected in-line to asegment of chain provides a lasting, visual indication that the ratedcapacity of the chain has been exceeded. It is connected directly towhat would otherwise be adjacent links of a chain; or between a chainand a chain attachment, such as a clevis hook. The overload indicatinglink or overload indicator 8 is marked or labeled with the ratedcapacity of the chain.

People using chain for vehicle recovery, towing, logging, lifting andother load bearing applications often do not know when they areoverloading, or exceeding the rated capacity, of the chain. Overloadinga chain has often resulted in personal injury or property damage if theunaware and uninformed user continues to load the chain to its breakingpoint, due to industry and government standards for safety factors inthe design and manufacture of chain, the yield point and ultimatetensile strength of an undamaged chain are both well above the ratedcapacity, or working load limit, of the chain. There is therefore, novisible indication to a user, such as elongation of the chain links,that the chain has been overloaded until the overload is in excess ofthe yield point and that much closer to ultimate failure. A relatedproblem is that someone using a chain that could have been used byothers does not typically know the condition or history of the chain, orthe risk of using it. Various devices are available today to monitor theload on a chain. They are, however, frequently not used due to suchdrawbacks as cost, availability, complexity, and the need for signalprocessing equipment.

One objective of the present invention is to provide a versatile,rugged, load bearing, self contained warning device that presents areliable and lasting visual signal, readily visible to a current orsubsequent user, to indicate a chain has been overloaded beyond itsrated capacity.

In a preferred embodiment shown in FIG. 13, the notch 30″ is a V-cutnotch that is cut at a 45% angle to the surface of the elongated side 12of strand 10 running parallel to the length of the strand 10.

Referring now to FIG. 17, a load bearing device 102 of the presentinvention having first and second load bearing connectors 104, 106interconnected by an overload indicator 108 to create a three-linksafety loop 111 is shown. The preferred embodiment shown in FIG. 17 is achain 102 including a modified welded link 109.

Referring now also to FIG. 18, the overload indicator 108 of the presentinvention is preferably made from a modified welded link 109 in which anamount of wire form material in a segment or a portion of a strand 110of wire form material of the welded link 109 is diminished in one of anumber of ways that result in a strand of wire form material that has asegment where the strand is weaker than in other segments of the strandand is therefore projected to break in this segment containing thediminished amount of material. The strand 110 of wire form materialincludes first and second elongated sides 112, 114. It will beappreciated that the overload indicator 108 can be effectivelyinterconnected to any two chain links in a chain that are not otherwiseinterconnected by a single chain link, thereby creating a safety loop ofat least two links, preferably three and any greater number than threeexcept as may be limited by cost and other practical concerns.

Referring now also to FIGS. 19-22, it will be appreciated that one ofthe ways a segment of the strand 110 of wire form material can bediminished to form a modified welded link 109 is to machine one of theelongated sides 112 to form a rounded notch 130 a, 130 b, 130 c, 130 d,as shown. The strand 110 has a generally uniform thickness C, which ismeasurable through a cross-section of the strand 110 generallyperpendicular to the length of the elongated side 112. The thickness Dof the strand 110 at the notch 130 a can also be measured in a similarmanner and it will be less than the thickness C of the other segments ofthe strand 110. In preferred embodiments, the thickness of the notch 130will be less than about 70% of the thickness of the other segments ofthe strand 110.

Referring now also to FIGS. 23-28, such an elongated side 112 may alsobe drilled out, preferably in the center of the wire form material toform openings or holes 136 a, 136 b, 136 c, 136 d, 136 e, 136 f. Thethickness C′ of the strand 110 is generally measured across across-section of the strand 110 perpendicular to the length of theelongated side 112 of the strand 110. The thickness D′ of the remainingmaterial on either side of the hole or opening 136 determined bymeasuring the inside diameter D′ of the respective hole and subtractingthat from the thickness C′ of the strand 110 to determine the thicknessof the remaining material.

In yet further embodiments, further notches in the elongated sides 112will also diminish the amount of wire form material in the diminishedsegment of the strand 110. Referring now also to FIGS. 29 and 30, aV-shaped notch 130″ made by a machining tool such as a mini-broach orthe like may also be included (see e.g. FIG. 29), as can a saw-cut notch130′″ made by a saw blade (see e.g. FIG. 30). The thickness D″, D′″ ofthe respective notches 130″, 130″″ and the thickness C″, C′″ of thestrand 110′ in each case are measured in the same manner as discussedabove in relation to the overload indicators 108 a-108 d discussed inrelation to FIGS. 18-22. It will be appreciated that other ways ofreducing the material present in the strand 110 of wire form materialmay be employed so long as the amount of wire form material is reducedas compared to an adjacent segment of the strand 110. While machiningand cutting may be used, it will also be appreciated that the strand ofwire form material could be formed to have a diminished amount of wireform material in one segment as compared with the other segments thathad a greater amount of material. In this way, a diminished segmentcould be created without machining or cutting the strand in any way.

Depending either on the amount of material present, the thickness of theremaining material, or any other measure of diminished material presencethat correlates with break strength, it is believed that the modifiedwelded links 109 or overload indicators 108 can be calibrated to providean indication of a load borne by the load bearing device 102 thatexceeds a load bearing capacity established for the load bearing device102.

Referring now also to FIGS. 18-22, an alternate load bearing device ofthe present invention may include any one of a series of overloadindicators 108 a, 108 b, 108 c, 108 d in which the strand 110 of thequick link 109 is diminished by creating a notch 130 a, 130 b, 130 c,130 d in the strand 110 to diminish the thickness of the strand anddiminish the amount of wire form material in a perpendicularcross-section passing through a length of the strand through thenarrowest portion of the strand 110 at the respective notch 130 a, 130b, 130 c, 130 d. This narrowing of the thickness of the strand, or, inan alternate embodiment discussed below, the reduction in the amount ofwire form material in the strand 110, is believed to reduce the strengthof the strand 110 at the point of this narrowing or reduction ofmaterial so as to create a weakness in the strand 110 where the strand110 will break in a predictable manner, when exposed to loads whichexceed the load bearing capacity of the strand 110. This load bearingcapacity can be calibrated as discussed below in order to provide anoverload indicator 108 which will indicate that an established loadbearing capacity for a particular load bearing device 102 including anoverload indicator 108 has been exceeded when such a load bearing device102 is exposed to an excessive load.

Although the load bearing device shown in FIG. 17 is essentially a chainhaving a series of chain links and an overload indicator 108 of thepresent invention, it will be appreciated that the load bearingconnectors 104, 106 may also be made of other load bearing connectorssuch as cables, straps, ropes, wire ropes and the like that areinterconnected with the overload indicator of the present invention.Although not required, the safety loop 111 shown in FIG. 17 ispreferred. Any number of equivalent safety loops may be used inassociation with alternate load bearing devices including safety loopsmade from ropes, wire ropes, cables, straps and the like that aresecured to the respective load bearing connectors to secure them if theoverload indicator is exposed to an excessive load and subsequentlybreaks following such exposure.

Referring now also to FIGS. 29 and 30, the notch 130 of the presentinvention may be a narrowing in the strand 110 of a welded link createdby a grinding device of one type or another or by any other type ofdevice that will remove material to either create a narrowing in thestrand or simply reduce the amount of wire form material in a certainthickness of the strand 110 of the welded link. In FIGS. 29 and 30, twosomewhat different notches, 130″ and 130′″, are shown. These notches area v-cut notch 130″ and a saw-cut notch 130′″. In each case, the amountof material at the narrowest point of the respective notch is reduced,thereby reducing the breaking force required to break the strand at therespective notch. In the present application, the term “notch” means anarrowing in a strand of wire form material. The narrowing may becreated either by cutting away existing material in a pre-formed strandof wire form material, or, alternately, by creating a strand of wireform material having a narrowing.

Referring now also to FIGS. 7-12, the overload indicator 108 of thepresent invention may also include a segment of a strand 110 of wireform material in which the amount of wire form material in a horizontalplane passing through the strand 110 of wire form material is reduced bydrilling a hole 136 or otherwise creating an opening 136 in the strand110 of wire form material. In this way, the amount of wire form materialin this particular strand of wire form material is reduced so as toreduce the breaking force required to break the strand at thisparticular segment. It will be appreciated that a series of openings orholes, having a variety of shapes, may be created in a strand of wireform material to reduce the amount of material in the strand, therebyreducing the breaking force required to break the strand. In each case,it is believed that the amount of force required to break the strand 110at the point at which the amount of wire form material in the strand isreduced can be calibrated so as to create a predictable breaking forcethat will break the strand when such a force is borne by the strand. Inthis way, a series of overload indicators 108 may be created, calibratedand used to provide an indication of the exposure of a load bearingdevice to a load which exceeds an established load bearing capacity forthe particular load bearing device 102. It will be appreciated, that aload bearing device 102, including an overload indicator of the presentinvention, will provide an indication to manufacturers when their loadbearing devices have been misused by purchasers. In particular, if aload bearing device having a specific load bearing rating is used andexposed to a load greater than the established load bearing capacity forwhich the load bearing device is rated, the overload indicator willbreak, providing clear evidence of its exposure to a load exceeding theestablished load bearing capacity.

As noted in FIGS. 1 and 2, the overload indicator may also include aserial number 140 which is etched, stamped or otherwise imprinted on theload bearing device. The same serial number may also be secured to therespective load bearing connectors 104, 106, so that upon failure of theoverload indicator, efforts to replace the overload indicator with adifferent overload indicator can be monitored.

As indicated above, the overload indicator 108 will have a serial number140 to identify the particular overload indicator 108. In preferredembodiments, the load bearing connector may also have a serial number140 so that the load bearing device may be identified and correlatedwith the particular overload indicator 108 interconnecting therespective load bearing connectors of the load bearing device with theoverload indicator actually incorporated in the device by themanufacturer. It will be appreciated that utilizing these serial numberswill provide manufacturers with information to help control tampering byusers following exposure of a load bearing device 102 or overloadindicator 108 to a load which exceeds the working capacity or ratedcapacity set for the particular indicator 108 or device 102.

In preferred embodiments, the strand 110 of wire form material used tomake the quick link 109 for modification to be an overload indicator108, will be made of steel containing at least about 0.12% carbon,preferably at least about 0.16% carbon, most preferably about 0.22%carbon and sufficiently heat treated to raise the tensile strength ofthe overload indicator 108 to that sufficient to meet tensile strengthrequirements for inclusion in an overhead chain load bearing device inthe United States of America. It will be appreciated that heat treatingis an art that is well known and that those of skill in the art canachieve the goal they wish to achieve when they are asked to heat treata higher carbon steel of the type discussed. Heat treating generallyinvolves heating the steel to a temperature of at least about 1600degrees F. or until the steel is “red hot”. The heat is then quicklydissipated, by placing the steel in a cooler liquid to “quench” theheat. The steel is then tempered by heating the steel again. Each typeof steel is treated somewhat differently and many approaches may betaken, most of which are well know in the art.

The present overload indicator 108 preferably includes first and secondelongated sides 112, 114 and a connector 116, interconnected with aconnecting end 122 of the overload indicator, preferably for threadableconnection to a connectable end 124 of the overload indicator to close agap (not shown), which exists between the connecting end 122 and theconnectable end 124 of the overload indicator 108. In preferredembodiments, the overload indicator will have a notch 130 in the secondelongated side that creates a narrowing in the wire formed materialwhich reduces the strength of the material and the load bearing capacityof the material at that point. The amount of material that is removed increating the notch may be varied and the amount of material whichremains will correlate with the amount of the load bearing capacity ofthe preferred overload indicator.

EXAMPLE 4

Commercially available carbon steel (SAE 1008 STEEL) chains wereprovided to make preferred overload indicators of the present invention.A single, formed only carbon steel “C” link is “woven” into each chainto link two different links that are separated by a three link “loop”similar to that shown in FIG. 17. The “C” link is crimped to bring theopen ends together and the open ends are then welded to close the linkand form a welded link that is essentially the same as the other links,except that it connects links that are separated by three additionallinks in the chain. The closed and subsequently welded link is the sawcut a predetermined distance at the mid-point of the side of theclaosed, welded link opposite to the welded side of that link. After thesaw cut, the welded link will have a strand or side opposite the weldedside or strand similar to the strand 110 shown in FIG. 30. The saw cutsare of various distances into the strand to form a series of loadbearing devices of the present invention just like the load bearingdevice 102 shown in FIG. 17, except that the overload indicator willhave a saw cut as shown in FIG. 30. The saw cut is machined to createnotches of various depths generally in the center of the side of thewelded link opposite the side having the weld. The thickness of theremaining wire form material at the saw cut notch is measured using anoptical measuring device. The load bearing devices made with each of therespective overload indicator samples are tested to determine its peakload by placing a continuously increasing load upon each load bearingsample using a Satec Tensile Strength Tester. The data for breakingstrength for four overload indicators saw about half way through, aboutfive-eighths way through and about three-quarters way through,respectively, is reported in Tables 5 and 6 below. The data is alsoplotted against remaining material thickness at the notch in FIG. 31A togenerate a best fit line showing the relationship between break strengthand remaining material thickness at the notch and against notch depth inFIG. 31B. The data is reported in Table 1 and a plot of the data isshown in Graph 1. TABLE 5 NOTCHED LINK TESTING THICKNESS OF WIRE DIA.WIDTH OF MATERIAL ULT. BREAK (Inches) NOTCH DEPTH REMAINING PULL TYPE ½WAY LINK 1 0.391 0.191 0.200 8803 WELD/NOTCH LINK 2 0.391 0.193 0.1988239 NOTCH LINK 3 0.391 0.195 0.196 9015 NOTCH LINK 4 0.391 0.195 0.1968215 WELD AVERAGE 0.198 8,568 ⅝ WAY LINK 1 0.391 0.238 0.153 6771 NOTCHLINK 2 0.391 0.246 0.145 6211 NOTCH LINK 3 0.391 0.245 0.146 5888 WELD &NOTCH LINK 4 0.391 0.246 0.145 6106 WELD & NOTCH AVERAGE 0.147 6,244 ¾WAY LINK 1 0.391 0.289 0.102 5575 WELD & NOTCH LINK 2 0.391 0.291 0.1005378 NOTCH LINK 3 0.391 0.293 0.098 4967 WELD & NOTCH LINK 4 0.391 0.2970.094 4119 NOTCH AVERAGE 0.099 5,010

TABLE 6 Test Peak Maximum Size of Load at Counter Load Elongation SampleBreak Type Comments Link Grade Offset 21108 8803 3.36 1 WELD & ½ WAY 10MM P43 8519 NOTCH NOTCH 21109 8239 4.14 2 NOTCH ½ WAY 10 MM P43 7921NOTCH 21110 9015 2.29 3 NOTCH ½ WAY 10 MM P43 8556 NOTCH 21111 8215 1.764 WELD ½ WAY 10 MM P43 7793 NOTCH 21112 5575 2.86 1 WELD & ¾ WAY 10 MMP43 4793 NOTCH NOTCH 21113 5378 5.72 2 NOTCH ¾ WAY 10 MM P43 4652 NOTCH21114 4967 1.52 3 WELD & ¾ WAY 10 MM P43 4249 NOTCH NOTCH 21115 41194.25 4 NOTCH ¾ WAY 10 MM P43 3567 NOTCH 21116 6771 3.47 1 NOTCH ⅝ WAY 10MM P43 5955 NOTCH 21117 6211 2.73 2 NOTCH ⅝ WAY 10 MM P43 5617 NOTCH21118 5888 1.61 3 WELD & ⅝ WAY 10 MM P43 5141 NOTCH NOTCH 21119 61061.68 4 WELD & ⅝ WAY 10 MM P43 5256 NOTCH NOTCH

It is to be understood that even though numerous characteristics andadvantages of the various embodiments of the present invention have beenset forth in the foregoing description, together with details of themanufacture of load bearing devices and overload indicators of thepresent invention and the various steps of the method of making a loadbearing devices, but that this disclosure is illustrative only andchanges may be made in detail, especially in matters of additionalcomponent and/or steps in the method of making the various embodimentsof the present invention, all within the principles of the presentinvention, to the full extent indicated by the broad general meaning ofthe terms in which the appended claims are expressed.

1. A load bearing device calibrated to provide an indication of a loadborne by the load bearing device that exceeds a load bearing capacityestablished for the load bearing device, the load bearing devicecomprising: first and second load bearing connectors interconnected byan overload indicator; the overload indicator being calibrated toprovide an indication of a load borne by the load bearing device thatexceeds a load bearing capacity established for the load bearing device;the overload indicator including a welded link; the welded linkincluding a strand of wire form material; the strand of wire formmaterial having first and second portions, the first portion having afirst thickness containing a first amount of wire form material in aperpendicular cross-section passing through a length of the strand; thesecond portion including a diminished segment having a second amount ofwire form material in a perpendicular cross-section passing through alength of the strand which is less than the first amount of wire formmaterial, wherein the second amount of wire form material is calibratedin such a manner as to establish a projected peak load, which, whenborne by the overload indicator, can have sufficient force to break theoverload indicator proximate the diminished segment.
 2. The load bearingdevice of claim 1, further comprising a safety loop interconnecting thefirst and second load bearing connectors.
 3. The load bearing device ofclaim 1, wherein the overload indicator has a serial number affixed toidentify the overload indicator.
 4. The load bearing device of claim 1,wherein the load bearing device has a serial number affixed to a loadbearing connector.
 5. The load bearing device of claim 1, wherein thesecond portion includes a notch in the strand of wire form material. 6.The load bearing device of claim 5, wherein the notch is selected fromthe group consisting of a rounded notch, a V-shaped notch and a saw-cutnotch.
 7. The load bearing device of claim 1, wherein the second portionincludes an opening in the strand of wire form material.
 8. The loadbearing device of claim 1, wherein the strand of wire form material ismade of a steel material, including at least about 0.12% carbon, that issufficiently heat treated to increase the tensile strength of the steelto meet government strength requirements in the United States foroverhead chain lifting equipment.
 9. An overload indicator calibrated toprovide an indication of a load borne by the overload indicator thatexceeds a load bearing capacity established for the overload indicator,the overload indicator comprising: a welded link; the welded linkincluding a strand of wire form material having first and secondportions, the first portion having a first thickness containing a firstamount of wire form material in a perpendicular cross-section passingthrough a length of the strand; the second portion including adiminished segment having a second amount of wire form material in aperpendicular cross-section passing through the second segment; thesecond segment having a second thickness that is less than the firstthickness, wherein the second amount of wire form material is calibratedin such a manner as to establish a projected peak load, which, whenborne by the overload indicator, can have sufficient force to break theoverload indicator proximate the diminished segment to indicate that aproject load capacity less than established peak load has been exceeded.10. The overload indicator of claim 9, wherein the overload indicatorhas a serial number affixed to identify the overload indicator.
 11. Theload bearing device of claim 8, wherein the second portion includes anotch in the strand of wire form material.
 12. The load bearing deviceof claim 11, wherein the notch is selected from the group consisting ofa rounded notch, a V-shaped notch and a saw-cut notch.
 13. The loadbearing device of claim 8, wherein the second portion includes anopening in the strand of wire form material.
 14. A method of making aload bearing device calibrated to provide an indication of a load borneby the load bearing device that exceeds a load bearing capacityestablished for the load bearing device, the method comprising the stepsof: a) securing an overload indicator to first and second connectors ofa load bearing device such that the overload indicator will provide anindication of a load borne by the load bearing device that exceeds aload bearing capacity established for the load bearing device; theoverload indicator being calibrated to provide an indication of a loadborne by the overload indicator that exceeds the load bearing capacityestablished for the overload indicator; the overload indicator includinga welded link; the strand of wire form material having a first portionhaving a first thickness containing a first amount of wire form materialin a perpendicular cross-section passing through a length of the strand;the first portion being adjacent to a second portion; the second portionincluding a diminished segment having a second amount of wire formmaterial in a perpendicular cross-section passing through a length ofthe strand which is less than the first amount of wire form material,wherein the second amount of wire form material is calibrated in such amanner as to establish a projected load, which, when borne by theoverload indicator, will create a sufficient force to break the overloadindicator proximate the diminished segment.
 15. The method of claim 14,wherein the step of securing includes providing the load bearing devicewith a safety loop interconnecting the first and second load bearingconnectors.
 16. The method of claim 14, wherein the step of securingincludes providing the overload indicator with an affixed serial numberwith which to identify the overload indicator.
 17. The method of claim16, wherein the step of securing includes providing the load bearingdevice with a serial number affixed to a load bearing connector.
 18. Amethod of making an overload indicator for incorporation into a loadbearing device to provide an indication of a load borne by the loadbearing device that exceeds a load bearing capacity established for theload bearing device, the method comprising the steps of: a) providing awelded link; the welded link including a strand of wire form materialhaving first and second ends, the first and second ends defining a gapbetween the respective first and second ends; the welded link furtherincluding a disconnectable connector connecting the first and secondends of the strand of wire form material to form a continuous loop whenthe connector is connected to each of the respective first and secondends; the strand of wire form material having a first portion having afirst thickness containing a first amount of wire form material in aperpendicular cross-section passing through a length of the strand; thefirst portion being adjacent to a second portion having the samethickness; b) modifying the welded link by diminishing the amount ofwire form material in the second portion so that the second portionincludes a diminished segment having a second amount of wire formmaterial in a perpendicular cross-section passing through a length ofthe strand which is less than the first amount of wire form material,wherein the second amount of wire form material is calibrated in such amanner as to establish a projected load, which, when borne by the secondsegment, can have sufficient force to break the modified welded linkproximate the diminished segment.
 19. The method of claim 18, whereinthe step of providing includes providing the overload indicator with anaffixed serial number with which to identify the overload indicator. 20.The method of claim 18, wherein the step of modifying the welded linkincludes creating an opening in the strand of wire form material in thesecond portion by drilling through a portion of the strand
 21. Themethod of claim 18, wherein the step of modifying the welded linkincludes creating a notch in the strand of wire form material in thesecond portion.
 22. The method of claim 18, wherein the step ofmodifying the welded link includes creating a notch in the strand ofwire form material in the second portion, wherein the notch created inthe strand of wire form material is selected from the group consistingof a rounded notch, a V-shaped notch and a saw cut notch.